The invention relates to a reel furnace having a strip reeling device. The strip reeling device comprises a reel shaft, a reel drum supported on the reel shaft and at least one stirrup clamp. The reel shaft passes through a furnace wall delimiting the inner space of the reel furnace and is supported rotatably in supporting bearings outside the reel furnace. The reel drum and the at least one stirrup clamp are positioned with respect to one another by means of a connection element, and a gap for receiving a strip head is set between the reel drum and the at least one stirrup clamp.
Strip reeling devices of this type are employed preferably in conjunction with Steckel rolling mills for the winding, intermediate storage and unwinding of hot-rolled strip-shaped stock between successive rolling passes.
Steckel drums usually have a hollow-cylindrical drum body with a longitudinal slot which is coordinated with the maximum rolled strip width. The cylindrical drum body forms with its surface area the winding surface for the first strip turn, and the longitudinal slot forms an entry orifice for the strip head of the hot-rolled strip. Owing to the slot, there is an open cross section of the drum body which has a greatly reduced torsional moment of resistance, as compared with a closed cross section. This weakening of the drum body leads, during the period of use of the drum, to flattening of its circular geometry, varies the slot geometry and additionally gives rise, during winding, to strip tension fluctuations which have an adverse effect on the stability of the winding operation. Further, high local notch stresses in the drum casing arise at both slot ends. These stress patterns, the tendency to deformation and the influence of the high operating temperature curtail seriously the useful life of the Steckel drum, and therefore even after a production quantity of about 500 000 tons of hot-rolled strip, a drum change becomes necessary.
Reel furnaces having a strip reeling device of the type initially described are already known from DE-A 909 577, DE 21 10 317 A1 and GB-A 693 397. The reel drum in each case comprises a middle part, which is pushed on a reel shaft, and two drum segments mounted tiltably in lateral plates. A wedge-shaped reception orifice for the entering strip head of a hot-rolled strip is formed by the middle part and each of the drum segments. Immediately after the entry of the hot-rolled strip, the reel drum begins to rotate and winds up the hot-rolled strip. None of these known embodiments affords the possibility of an individual setting of the gap width as a function of the strip thickness of the entering hot-rolled strip and also of a defined clamping of the hot-rolled strip.
The multipart setup of a reel drum under axial spring tension, such as is known in a strip reeling device according to DE 21 10 317 A1, requires a complicated system of bosses, which, emanating from fixed stirrup elements, project into recesses of the individual reel drum elements and act as drivers, but at the same time also at least partially as stops for the entering hot-rolled strip. Even DE 21 10 317 A1 points to the high susceptibility to wear of these bosses and of the reel shaft elements which have to be equipped with particularly hard and wear-resistant coverings. Constructions of this type cannot be used efficiently under thermal loads of 800° C. to 1000° C.